This invention relates to an ink jet printhead which incorporates mass actuated ink ejection mechanisms. This invention also relates to a method of ejecting ink from a printhead.
The Applicant has invented a page width printhead which is capable of generating text and images of a resolution as high as 1600 dpi on a printing medium.
The printheads are manufactured in accordance with a technique that is based on integrated circuit fabrication. An example of such a technique is that which is presently used for the fabrication of micro electromechanical systems.
These fabrication techniques allow the printhead to incorporate up to 84000 nozzle arrangements. The nozzle arrangements are electro-mechanically operated to achieve the ejection of ink. The reason for this is that presently used techniques such as those based on the heating of the ink to achieve ejection are simply not suitable when the nozzles are packed in such a high density. Applicant has found that the heat build up is excessive and would result in failure of the printhead.
The Applicant has addressed this problem by developing manufacturing techniques which are suitable for manufacturing, on a micro electromechanical scale, nozzle arrangements which are independently operable to eject ink. Applicant has filed a large number of patent applications to cover this technology. Applicant has found that electro-mechanical operation of the nozzle arrangements results in heat build up which is substantially less than the heat build up of other systems, such as those based on the heating of the ink and on piezoelectric movement.
It remains a goal, however, of the Applicant to achieve as little heat build up as possible. It will be appreciated that this could be achieved by reducing, even further, the amount of work required to achieve the displacement of the ink. Applicant has found that, by actuating ejection mechanisms remotely and en mass and then selectively controlling individual operation of the ejection mechanisms, a substantial reduction in energy requirements can be achieved.
According to a first aspect of the invention, there is provided an ink jet printhead which comprises
at least one nozzle arrangement, the, or each, nozzle arrangement defining a nozzle chamber having an ink ejection port and the, or each, nozzle arrangement having an ink ejection mechanism for ejecting ink from the nozzle chamber and out of the ink ejection port, the, or each, ink ejection mechanism being repeatedly actuable by an actuator, at a desired frequency; and
at least one deactivator which is operatively engageable with the, or each respective, ink ejection mechanism and which is selectively operable to deactivate the, or each respective, ink ejection mechanism, the deactivator being connectable to a control system to control operation of the deactivator.
According to a second aspect of the invention, there is provided an ink jet printhead which comprises
a wafer substrate;
a plurality of nozzle arrangements formed at least partially from the wafer substrate in an integrated circuit fabrication process, each nozzle arrangement having two pairs of opposed walls that define a nozzle chamber, an ink ejection port and an ink displacement member which is pivotally connected to one of the nozzle chamber walls proximate an inlet of the nozzle chamber, each ink displacement member being repeatedly actuable on the application of a pulsed magnetic field to eject ink from the nozzle chamber through the ink ejection port, at a desired frequency; and
a deactivator that is positioned in each nozzle arrangement and that is connected to drive circuitry, the deactivator being displaceable, on the application of an electrical current from the drive circuitry, between an operative position in which the deactivator engages the displacement member to inhibit actuation of the ink displacement member and an inoperative position in which the ink displacement member is free to pivot under influence of the pulsed magnetic field.
According to a third aspect of the invention, there is provided a method of ejecting ink from an ink jet printhead, the method comprising the steps of:
repeatedly actuating a plurality of ink ejection mechanisms positioned in each of a plurality of nozzle chambers defined by each of a plurality of nozzle arrangements that further each define an ink ejection port so that ink can be ejected from each of the injection ports at a desired frequency; and
selectively deactivating the ink ejection mechanisms to control the ejection of ink from each ink ejection port.